BAGHDAD, Iraq — The U.S. military said Sunday its forces had captured an Iraqi allegedly responsible for the killing of a tribal leader who had helped organize local forces against al-Qaida-linked insurgents in al-Anbar province.

The slaying of Sheik Abdul Sattar Rishawi last Thursday was part of a plot by militants to kill leaders in the Anbar Awakening Council, a coalition of tribes, military officials said.

Rishawi organized the council to assist U.S. forces in battling al-Qaida in Iraq, which sought to control the Sunni-dominated province west of the capital.

Key to the plot, the military said, was Fallah Khalifa Hiyas Fayyas Jumayli, an Iraqi who also is known as Abu Khamis. Jumayli was arrested south of Ramadi, the provincial capital.

“He was involved in the planning and execution of the plot to kill the sheik,” said Rear Adm. Mark Fox, a military spokesman. “He was also plotting to kill other members of the Anbar Awakening Council. He was also involved in organized activities including car bombs and suicide attacks in Anbar province.”

U.S. forces captured several men in the past two months who allegedly worked for Jumayli by supervising bombings and other attacks, said Maj. Jeff Pool, a military spokesman.

Five days before Rishawi’s killing, soldiers captured members of the militant leader’s group, and afterward they were able to track down Jumayli. “The information which we received following his death directly implicated him in Sattar’s death in a clear and unmistakable way,” Pool said.

The Islamic State of Iraq, an umbrella radical group that includes al-Qaida in Iraq, claimed

responsibility for the killing in a Web site

declaration.

Saturday, the militants warned they would step up attacks during the monthlong observance of Ramadan, the Islamic period of fasting that began last week.

Sunday, nearly three dozen people were reported killed in gunfire and bombings across Iraq as military officials presented their case at a news conference that violence in the capital might be slowing.

Casualties in Baghdad fell from a monthly high of 2,221 last November to 980 killings in August, the U.S. military reported. The numbers could not be independently verified.

Referring to the surge ordered this year by President Bush, he added: “We always knew with the surge in forces, by the increased presence of boots on the ground in the 10 security districts, we would be successful in pushing them out.”

But the successive rounds of killings and retaliations, many of them driven by sectarian hatred and religious rivalries, continued in the capital Sunday.

Two municipal councilmen were killed in attacks by gunmen in the south of Baghdad; a mortar round killed one person and injured three others in east Baghdad, and private security guards allegedly opened fire west of downtown, killing nine people and injuring 15.

A dozen bodies, all male, were found in various parts of the capital.

Elsewhere, gunmen killed 14 people and injured seven others in an attack at a village called Ballor, northeast of Baghdad in Diyala province.

In Tuz Khurmatu, about 130 miles north of the capital, a suicide bomber killed six people at a restaurant. In Hillah, 65 miles south of Baghdad, a clash between tribesmen and gunmen left one bystander dead.

(Click here if you are unable to view this photo gallery on your mobile device) The Ruth Bancroft Garden in Walnut Creek celebrates the life of its founder Ruth Bancroft who died at 109 on November 26, 2017. The Ruth Bancroft Garden is a nonprofit public dry garden that was planted by Mrs. Ruth Bancroft in 1972 and was opened to the...